The invention concerns a mayonnaise-like product with a high fat content, with an emulsifier other than egg yolk and with a low pH and a process for its manufacture.
The preparation of acid oil-in-water emulsions with high fat content and with emulsifiers other than egg yolk is known in the art. Usually, emulsions prepared with low molecular weight (LMW) emulsifiers have low viscosity. Examples are emulsions prepared with ethoxylated monoglycerides, diacetyl tartaric acid ester of mono- and diglycerides and hydrolysed lecithins. High viscosity emulsions are possible with polyoxyethylene-(20)-sorbitan monostearate at concentrations higher than 1%, but the taste is unacceptably bitter. Generally, viscosity is increased in oil-in-water emulsions by using thickening or gelling agents like polysaccharides, gums or cold swelling starches, but when it is used in high fat emulsions prepared with LMW emulsifiers, the result is poor texture or destabilisation of the emulsion.
On the other hand, high molecular weight (HMW) emulsifiers (proteins) are known for their emulsifying function and ability to lend viscosity to emulsions. Generally, milk proteins combined with thickeners are used for this purpose in low to medium fat emulsions (1-55% fat). Emulsions with higher fat content are difficult to prepare because the complex structural properties of proteins directly influence their emulsifying functions. In the food industry, acidified protein solutions are advantageous for industrial processing due to microbiological safety. Regarding the effects of acid, proteins can be divided in two general categories:
1. Those with a generally flexible, random coiled structure like casein and skim milk powder, which precipitate upon direct acidification and thereby lose their emulsifying properties. This makes the emulsification with oil and the production of high fat emulsions with directly acidified solutions impossible.
2. The proteins with generally compact, inflexible structures, like whey, soya and pea proteins, which are all mixtures of different types of serum albumins and globulins. Although these proteins generally do not precipitate upon acidification, they still undergo structural changes at the iso-electric pH, yet in most cases, emulsification with oil is still possible. High fat emulsions prepared in this way have high viscosity, but they become gelatinised during storage and result in rough texture.
In the case of U.S. Pat. No. 3,892,873, supplementary emulsifying agents, like ethoxylated monoglycerides, polyoxyethylene sorbitans, mono- and diesters of higher fatty acids and glycerin, may be used.
It is known that emulsifying properties of proteins are improved when they are first emulsified with oil before heating and/or acidification. The drawbacks of this solution is first that it is not possible to operate continuously but batchwise and secondly that there is a greater chance of contamination.